A step-by-step mechanism which is configured as a clamping roller mechanism is known, for example, from DE 198 54 931 A1. In interaction with a clamping roller locking mechanism, the clamping roller step-by-step mechanism forms a setting device for adjusting a motor vehicle seat. The driven shaft of the clamping roller locking mechanism can be coupled to the driven element of the clamping roller step-by-step mechanism, the driven shaft and the driven element being mounted in or on a common housing. Overall, the setting device according to DE 198 54 931 A1 is a proven construction.